The Halsted and Ashland-63rd Street stations will close Friday night at 10 p.m. and reopen Monday at 4 a.m.

The improvements are part of a nearly $20 million project. The CTA says stations will be able to accommodate additional trains during the Red Line south construction projects, which begins next month.

"The Green Line is an important transportation option for residents of the South and West sides," said Mayor Rahm Emanuel. "The investments we are making will offer long-term benefits as well as improve the experience for commuters relying on the Green Line during the Red Line reconstruction this summer and beyond.

Improvements include extensive trackwork on the southern Green Line and Ashland/63rd and Cottage Grove branches, such as replacing rail ties, tracks and upgrading signal and switching equipment, according to a press release from the CTA.